1. Field of the Invention
The present invention relates to novel organopolysiloxane compositions that are storage-stable in the absence of moisture, but curable into self-adhesive elastomeric state in the presence thereof, and, more especially, to novel storage-stable organopolysiloxane compositions containing an .alpha.,.omega.-dihydroxydiorganopolysiloxane, an acyloxysilane crosslinking agent and a bonding agent which comprises (i) admixture of an aminoorganosilicon compound bearing a primary amine substituent and an organosilicon compound bearing an epoxy functional group, or (ii) reaction product between such aminoorganosilicon/epoxyorganosilicon compounds.
2. Description of the Prior Art
One-component organopolysiloxane compositions containing an acyloxysilane crosslinking agent, and, generally, also an inorganic filler and a curing catalyst, have long been known to this art. Such compositions are described, in particular, in U.S. Pat. Nos. 3,077,465, 3,382,205, 3,701,753, 3,957,714, 4,115,356, and 4,273,698, and in FR-A-No. 2,429,811 and FR-A-No. 2,459,820.
These compositions are particularly useful in coating and jointing applications and, notably, as sealing agents in the construction industry for producing glazed structures.
For this particular application, the hardened elastomer must have a relatively low modulus of elasticity and, above all, adhere strongly to glass and to the material forming the structure in which the glass is mounted, such as wood, aluminum, concrete, PVC (polyvinyl chloride), natural and synthetic rubbers, stone, earthenware and brick.
However, the elastomers produced from compositions containing acyloxysilane crosslinking agents generally exhibit insufficient bonding to certain substrate materials employed in the construction industry, aluminum and PVC in particular. Various additives have been proposed to this art for incorporation into such compositions with a view to remedying this deficiency.
Thus, U.S. Pat. No. 4,115,356 describes a trialkoxysilane bearing an epoxy functional group useful as a bonding agent for silicone elastomer compositions comprising a polyacyloxysilane crosslinking agent.
A typical such silane is: ##STR1## .gamma.-glycidoxypropyltrimethoxysilane.
It is also known to the art that a bonding agent comprising the reaction product or a simple mixture of an aminopolyalkoxysilane and an epoxypolyalkoxysilane may be used in two-component (EP-A-No. 178,751) and one-component (EP-A-No. 221,644) silicone elastomer compositions containing polyalkoxysilane crosslinking agents.
It too is known that aminosilanes bearing a primary amine substituent may be used in one-component (see, for example, EP-A-No. 021,859) or two-component (see, for example, U.S. Pat. No. 3,888,815) alkoxyorganopolysiloxane compositions, and in organopolysiloxane compositions containing ketiminoxysilane crosslinking agents (see, for example, FR-A-No. 2,074,144).
Nonetheless, one skilled in this art would discount the use of such type of silane in one-component organopolysiloxane compositions comprising acyloxy groups, as these acid formulations always contain small amounts of free carboxylic acid which, by reacting with the primary amine, produce water that causes the composition to crosslink. Hence, these compositions are not stable under storage conditions.